A common question from aerospace and defence customers is: βDo we need MIL-SPEC qualification for our conformal coating?β
The short answer is: sometimes β but only when it is contractually required.
Confusion usually arises because legacy military standards are still referenced on drawings, purchase orders, or coating datasheets, even though the underlying standards landscape has changed.
For a full explanation of how military (MIL) requirements relate to modern conformal coating standards, see: MIL-I-46058C (Cancelled) & MIL Standards for Conformal Coating
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When is MIL-SPEC actually required?
In practice, manufacturers usually know they require MIL-related compliance when:
- The product is for a military or defence programme
- MIL requirements are explicitly called up on the customer drawing
- The purchase order or contract includes MIL flow-down requirements
If none of these are present, βMIL-SPECβ is often being used as shorthand for high reliability rather than a defined manufacturing requirement. This is where misunderstandings commonly occur.
Be cautious with datasheets claiming βmeets MIL-I-46058Cβ
Many conformal coating datasheets state that the material βmeets the requirements of MIL-I-46058Cβ. This wording should be treated with caution.
MIL-I-46058C is a cancelled standard, and simply stating compliance does not mean the coating has been independently approved or qualified. In many cases, the claim refers only to internal or historical test data.
Where defence programmes genuinely require MIL-style material qualification, customers will often expect evidence beyond a datasheet statement.
What is the Qualified Product List (QPL)?
Historically, conformal coatings tested against MIL-I-46058C were listed on the Qualified Product List (QPL).
The MIL-I-46058C Conformal coating standard has been inactive for new designs since the late 1990s, but QPL listings are still referenced in legacy documentation and long-lifecycle programmes.
Coatings appearing on the QPL would have undergone independent third-party testing rather than self-certification. This is an important distinction.
However, the presence (or absence) of a coating on the QPL does not automatically determine its suitability for modern programmes. What matters today is how customer requirements are defined and verified.
What is normally used instead today?
Modern defence and aerospace programmes typically rely on a combination of:
- IPC-CC-830 for conformal coating material performance and qualification
- IPC-A-610 for workmanship and acceptance criteria
- Customer drawings and specifications defining coverage, keep-out zones and inspection evidence
MIL requirements are therefore usually met through industry standards plus contractual flow-downs, rather than through a single active βMIL-SPECβ document.
Need to understand how the standards fit together?
The Conformal Coating Standards Hub brings together SCHβs guidance on IPC-A-610, IPC-CC-830, IEC 60664, UL 746, NASA workmanship standards and how they relate to conformal coating and Parylene.
It is designed to help engineering, quality and procurement teams understand:
- What each standard actually covers
- How acceptance, material qualification and inspection requirements interact
- Where legacy MIL references still appear β and how to interpret them safely
You can also explore related hubs covering Design, Inspection & Quality and Parylene Coating.
If you need help interpreting customer requirements, legacy MIL references, or selecting compliant coating materials and inspection criteria, contact SCH Services.
π Call: +44 (0)1226 249019 Β | β Email: sales@schservices.com
